Realization of Focused Beam and Shaped Beam Transmitarrays Based on Broadband Unit Cells

A focused beam and a shaped beam four-layer transmitarray (TA) antenna operating in the K-band have been designed, fabricated, and measured. Four-layer unit cells allowing a transmission phase range of 360 degrees are used. The gain of the beam-focusing TA is 30.3 dB at 19 GHz with an aperture efficiency of 34.9%. Compared with TAs proposed in the literature, the presented antenna bandwidth is almost two times larger with a -1 dB gain bandwidth of 18% and a -3 dB gain bandwidth of 25.5%. A second TA radiating a shaped beam was designed, and its measured pattern correlates well with theoretical calculations. The sensitivity of the proposed unit cells to fabrication errors and the effect of oblique incidence are also studied.